Welding device



19, 1939- w. GLADITZ 2,183,908

WELDING DEVICE Filed March 6, 1937 2 Sheets-Sheet 1 WNW.

wvmfr dbl-ta, C159,,

W. GLADITZ WELDING DEVICE Dec. 19, 1939.

2 Sheets-Sheet 2 Filed March 6, 1937 Patented Dec. 19, .1939

.UNITED' STATES PATENT OFFICE Application March a, 1931, Serial No, 129,304

' In Germany March 6, 1936 2 Claims. (Cl. 2194) My invention relates to the art of welding, at l3, which extends through a corresponding known as resistance welding, for uniting metal hole in the short pressure handle I and at its parts. free end carries a nut l4. Intermediate the lat- With the present welding apparatuses freter and the pressure handle I is provided a heliquently a welding operation cannot be carried cal compression spring shown at l2, which en- 5 out because of the undue size and the great circles the stud I3. This compression spring, weight of the welding apparatus, which makes it however, does not bear with its ends directly impossible to get to the welding place. Also such against the pressure handle I and the nut H, heavy welding apparatuses are difllcult to manipbut against interposed plates shown at [5 and i0 ulate, making it necessary to take the parts to Hi, which carry the contacts I! and I8 of the 10 be welded to the welding apparatus, which, primary circuit of a transformer. These conhowever, in many cases can not be done because mo up n the p g 12 being Compressed a of the size and the weight of the parts to be definite amount, are closed, with the result that welded, a current passes then through the electrodes ll The present invention more particularly relates placed in the electrode carriers3 and 4. By n 15 to spot welding and one of theobjects of this adjustment of the nut l4 the tension of spring invention is to produce a welding tool which, l2 can be varied to correspo d o a predeterbecause of its convenient shape and its small mined welding pressure. 7 weight, enables it to be readily connected to a I de ed. the handles 5 and a y be 0 vflexible cable, to be easily manipulated and to be fi W h a insulating Covering S o at a used in welding places difficult of access. whi h. w as a rule. w ll n be ry.

A further object of this invention is to so since the voltage in said handles will not exceed design the Welding tool that the welding operatwelve v lts. At 9 is sh wn a spring tend n tion only commences, when the electrodes rest o Sprea t e- 5 d 3 apart to thereby on the work with a predetermined pressure. facilitate the manip f e tool.

Another object of the present invention is to With reference to Fig. 3 0f the draw s. I W provide a welding tool in which the electrodes now describe, how the circuit including the weldare automatically disconnected when the desired ing electrodes is automatically opened, when the amount of welding has been effected, that is to desired welding eifect has been accomplished,

say, when a predetermined strength of current which is the case when the strength of the cura has been established. rent in the primary and secondary, which dur- In the appended drawings, on which I have ing thewelding operation increases, has reached shown, by way of illustration, an embodiment of a predetermined maximum value. ThisI acmy invention, Fig. 1 is a side elevation of the complish by p v d for s an n the secwelding tool and Fig. 2 a front view thereof; Fig. ondary 2| a suitable relay 2 corresponding to a 3 shows the tool together with the switch mechathe maximum current value. nism and the circuit diagram, while Fig. 4 shows At the end of the welding operation the a detail; Fig. 5 shows a modification. strength of the current in the secondary has in- As shown on the drawings and more particucreased to such an extent that the magnetic acm larly in Fig. 2, the welding tool is made in the tion of the current will overcome the weight 01' w shape of a pair of tongs provided with the two the contact arm and will attract the armature. jaws shown at I and 2. At 3 and 4 areshown By means of a pin of an insulating material a the electrode carriers, made for example of copcontact spring 21 is operated thereby, which per, which are mounted on the jaws, being insucontact spring in making contact with a second 5 lated therefrom by suitable bearing elements 5. contact closes the electric circuit 21 and 2G At 6 is shown a long handle which is made to said relay 22 and back over the transformer integral with the jaw 2, whereas at 1 is shown 33 and the contacts I1 and I8 carried by the a short handle, hereinafter called the pressure pressure handle I. As a result, the contact arm handle, which is made integral with the Jaw l. 32' of the relay 22 is attracted, the contact be- At 8 is shown a separate third handle, similar to tween 29 and 30 is broken and current will no 50 handle 6; the three handles 6, l and 8 are held longer'fiow through the coil of the element 34 together by a single pivot pin I0. At 9 is shown with the result that the contact arm 3| by its a recess in handle 8 to receive the pivotal end spring is returned to its original position. At of the separate handle 8. the same time, the contact at 3| is opened, which 5 Into the latter there is screwed a stud shown heretofore had held closed the main circuit, so u that no current now flows through the transformer 23 and the welding electrodes carried by the holders 3 and 4. Thus, the welding operation is automaticaily terminated.

The contacts 21 and 28, however, are in contact with each other for a brief time only and since the contact arm 24 directly after the welding current has been disconnected returns to its original position, no current would flow through the relay 22 with the result that at 29 and 30 the contact would again be closed, whereby also the contacts 31 by the attraction of the arm 3| would be closed again with the result that the welding operation could again commence. To prevent this, however, an auxiliary contact 32 is provided, which directly after the interruption of the contacts 29 and 30 causes current to continue to flow through the coil of relay 22, until by hand the contacts I! and I8 carried by the pressure handle 1 are likewise opened so that the tool is ready now for a fresh welding operation.

In order to insure greater safety, there is used for the operation of the contacts l1, I8, 29, 30 and 32 and the coils of the relays 22 and 34 a weak current, which I accomplish by the interposition of a small transformer 33, whereby the voltage is considerably reduced, for example, to twelve (12) volts. Only through contact 3| flows a current having a voltage of 220 volts.

In the secondary 25 and 26 the voltage for the resistance welding is only 2 to 8 volts so that all parts of the tool can be handled without any danger or risk of shocks,

The easily movable flexible current supplying cables 25 and 26 from the transformer 23 to the tool may be water-cooled by being enclosed over their entire length in a rubber hose 35, in which circulates a current of water.

It may be further noted that the transformer and the electric switch mechanism are enclosed in a casing, which, by being mounted on rollers or in a suspended position, may be readily moved from one place to another and which, especially because of the flexible and easily movable cables 25 and 26, permits the tool to be used within a large range of movements.

As shown in Fig. 5, the contacts indicated at H and [8' may be directly provided on the handles of the tool.

I claim:

1. A manual spot welding tool consisting of a pair of tongs comprising two jaws and handles therefor, holders for the welding electrodes detachably mounted on said jaws being insulated therefrom, a third handle operatively connected with one of said handles, a common pivot connecting all said handles, an electric contact carried each by one of said first mentioned handies and said third handle, and a compression spring intermediate said first mentioned handle and said third handle permitting said contacts to be closed only after having been compressed to a predetermined extent by the operation of said third handle.

2 A manual spot welding tool consisting of a pair of tongs comprising two jaws and handles therefor, holders for the Welding electrodes detachably mounted on said jaws being insulated therefrom, a third handle, a common pivot connecting all said handles, a stud laterally extending from said third handle operatively connecting said third handle with one of said first mentioned handles, an electric current carried each by said first mentioned handle and the stud extending from said third handle, and a compression spring intermediate said first mentioned handle and said third handle and permitting the closing of said contacts only upon being compressed to a predetermined extent by the operation of said third handle.

WALTER GLADITZ. 

